Method of treating clay



May 20 1941- P. D. BARTON I 2,242,639

vMETHOD TREATING CLAY Filed March 29, 1958 2 sheets-Sheet 1 Arme/vens.

May 2o, 1941. P. D. BARTON 2,242,639

METHOD oF TREATING CLAY Filed March 29, 1938 2 Sheets-Sheet 2 Arran/fn?.

Patented May g0, 1941 f UNITED i y STATE-s PATENT?QF'FICE' y METHOD o FTREATING citarV Y Paul D. Barton, Chester County, Pa., assignor to SunOil Company, Philadelphia,

tion' of New Jersey Pa., a corpora- Abplicaiio March 29, 193s, serialNo. 198,794

8 Claims.

The present invention relates to a process and apparatus for recoveringfilter clay which has been used to purify lubricating oil and moreparticularly to a -process wherein a substantial portion of the oiladsorbed' by the clay is recovered,

has not been `subsequently subjected toa caustic wash, to neutralize theoils.y e y K It is therefore an' object of the present invention totreat contact materials 'of the clay type, lwhich have been used eitheras percolation or contact filtration purifying agents for lubricatingoils, tol recover therefrom lubricating oil which has been adsorbed bythe clay, and tol vert it into marketable products.

Other and further objects of the invention will appear as thedescription progresses.

Briey stated, the invention consists in admix then conlng the clay withvhot water and passing it to a leaching pit which has been. previouslyfilled with 'hot-water. As Vsoon as the pit isiilled, hot water isrpassed up through the clay Aby admitting it at a multiplicity of placesover the floor of the pit so as to cause a steady upow of Water throughthe clay at all portions of the pit. The hot water passing through theclaybed leaches oil from'the .clay and this mixture together with somefines overflows into a separator pit having mechanicalprovisionsiorskimming the oil from the surface of the separator pit,and. for carrying it off in admixture with somewater to a final oilsettling Some `of the fines which pass ,over with vthe oil. and water tothe separator pit settle'and are 'returned' tothe Primary leaching pitby- A means ofv an eductor and` are evenly distributed over the clay anwater in the leachingf pit soas -not toA cause an gitation ofthe claywhich would y,breakup-the bed. 'I'he .excesswwater from the separatorpit is removed, heated, and passed back to the bottomvof the clayleaching pit, or is used asa medium for conveying further clay to the 1leachingpit. from the lter. --amoun t of o il has beenremovedfrom theclay After the desired by the water in the leaching pit, the clay is yatmosphera'causing the oil admixed therewith to f passed to a suitableseparator for removing the major portion of the water from vthe claywhich is then passed to a furnace where itis `burned in either areducingor `an oxidizing atmosphere.

If the clay is to be revivied for re-use, as much oil as possible isremoved therefrom during` the leaching step, and the clay issubsequently burned in an oxidizing atmosphere to completely remove theoil remaining therein. If, however, the clay. is. to be used for themanufacture of black pigment, a portion of the oil is left in the clayand the clay is then burned in a reducing bereduced to carbon;L f

If la carrier of insecticide powders is to be manufactured from theclay, it is washed exactly as Vif it is to be revivifed and is thendried, after whichit is thoroughly ground, preferably pulverized, tosuch an extent that it will pass through a 200 mesh screen, someparticles of course being much finer than necessary to pass throughcloth of that :neness` It is'characteristie of these carrier agents thata certain amount of oil. preferably 5% t'o 10% by weight must be. evenlyincorporated therein in order to more firmly hold the insecticide powderin admixture therewith and so thatparticles will adhere to plants,sothat when-the wholeis dusted on orchards, plants etc., an evencoverage of the insecticide ingredienty is achieved. Heretofore it hasbeen necessary to grindeither kaolin clay orclay of another type to theproper degree of neness and then, by alengthyand consuming process,spray the powder with oil while constantly mixing it. It is of courseapparent that if too much oilvis added thene powder will'agglomerate andif toe little oil is added the powder will not hold thev insecticide asit should.

Whenthe clay is treated in the present leachingpits, a1l'. of the oilcannotbe removed and the amountwhich is left after treatment b'y the npresent process can be so controlled that ju'st'the right .amount of oilremains therein to acco'm- -l plish the desired purpose after the clayhas been ground to the proper degree of neness. Itis of course to beunderstood that clay, to which an A amount of oil-in excess ofthat'desired in the nal product has been intentionally added in order toinsure in the final product even' distribution of the oil throughout theclay, is the equivalent of spent kfilteringclay containing an'ramount ofoil in excess of that desired inthe finished product, The waste waterpassing from the leaching 4 in thev second leaching pit or settling pit.These iines may be recovered either by further settling, illtration,electrical precipitation or other means, and since they contain theproper amount of oil, they may be used after drying as a carrier agentfor powdered insecticides. 1

A'furnace of the rotaryhearth type, such as a Nichols-Herreshoil, isused to burn the clay. In the rst one or two hearths any water left withthe clay will be evaporated and will cause further oil to be steamdistilled from the clay. The oi-l so vaporized passes oil' with the fluegas from the furnace which is passed to a flue gas washer A where theoil is condensed and returned to the leachingl pit with any nes whichmay be carried of! by the ilue gas.

From the furnace the burned clay is Passed to .a cooler and conveyor andthence if the furnace has been run with an oxidizing atmosphere in orderto burn substantially all of they carbon from the clay, the clay ispassed to storage for re-use or is disposed of if not fit for 'furtheruse.- If, however, the furnace has been run with a reducing atmosphereso that the oil in the clay is reduced to carbon and the mixture otcarbon and clay thus obtained isto be used asa pigment the clay from thecooler is passed to a ball mill wherein it is finely ground. From theball mill the ground clay with its contained carbon is blown to acyclone separator wherein the air used to convey the ground clay isseparated from the clay. From the cyclone separator the ground clay orpigment `is passed to a classifier of the 'centrifugal type, wherein anyunground abrasive material present in the ground clay is removed. Fromthis classiiierthe clay is passedto a secfond classifier, usually of thecentrifugal type, wherein clay having the proper flnenessY for use aspigment is separated from that which is too coarse for use as pigment.'I'he coarse material is returned to the ball mill for re-grindlng, andthe finished pigment is passed to packing equipment.

- A better understanding of the invention will be had by reference tothe accompanying drawings,

`which are a diagrammatic representation of -one form of apparatus inwhich the present invention may be carried out.

I represents a illter which may be either of the percolation or contacttype. 2 is a hopper into which the c lay may be dumped, for feeding intoan eductor 3`to which hot water heated to a temperature of say 120200 F.is fed through line 4.

- from-the bottom of the separator or settling tank I6 through line I1,and is returne to the system. Oilwhich is separated in ta 6 is withdrawnthrough a line I8. A 5' The nes which settle by gravity in the pit I2are accumulated by the flights on I3 into sump I9 from which they arepicked up by means of an eductor 20 to which water from line 2I is fed.The admixture of ilnes and water is passed through -line 2Ia to the Weirbox 22 from which it overilows into the clay leaching pit. The sepa-Arated water from pit I2 is withdrawn through line 23 by means ofcirculating pump 24 which forces it into line I0. A portion of thiswater may be by-passed through line 25 to heater 23, wherein it isheated by steam admitted through line 21. This heated water is thenreturned to the circulating pump through line 23. A further water outletline 23 is provided in separator pit I2. This water is withdrawn bymeans of pump 30 and is passed to line 3 I After the clay in the pit 3has been leached to the degree required, it is removed from the pit bymud pump 32, taking suction on the bottom of the pit, through line 33.lPlaced within the bottom of the pit 6 is alrestricted trough shapedsump 34 into which water is forced through jet pipes 35 and 35awhichkparallel pipe 33. The

water so admitted serves to mix as much water as desired with the clayand water mixture withdrawn by means of mud pump 32. It is evident thatif mud pump 321s operated at a 'constant speed, the more water which isadded through lines 35 and 35a, the less clay will be picked up with thewater passing up through line 33 to the mud pump 32. The mixture ofleached clay and water passing from the mud pump is forced through line3 6 to a separating device 31, wherein substantially all excess water isseparated from the clay. This separator 31 may be of the type utilizingradial plows or scrapers 33 which serve to raise the clay from thebottom of the sepai rator, de-water it by the compression caused inWithin the eductor the wateig from line 4 mixes with thel clay and themixture in the form of a slurry passes through line 5 to a clay leachingpit 6,the pit 3 having previously been filled with hot water of aboutthe same temperature as that mixed with the clay in the eductor 4. "Thefloor of the pit 6 is covered with a system of perforated pipes 1 whichare fed withhot water through lines 3 and 3 from-pipe I3.- The wateradmitted from the pipes 'l passes upwardly through the clay in the pit 3carrying withit oil from the clay andalso a small amount of finespresent in the clay. This admixture of water, oil and nes overilows theweir I I and passes into the oil separator pit I2. I

The oil separator pit I2 is provided with suitable means such as acontinuously revolving belt I3 having raised or ribbed portions or ightsthereon, for carrying the oil separating fromthe water and nes in pit I2overto an oil skimmer or trough I4, from whence it is passed throughline plowing it up, and then, by means of a vane, force it out .on theperipheral ledge 39, from'which it falls down chute 40 to the furnace.

'Ihe furnace 4I may be of the Nichols-Herreshoif multiple hearth typehaving a series of central and annular hearths set one above the otherso that the clay is caused by means of rabble arms 42 to pass downwardlyfrom one hearth tothe other. Heat is supplied by burners placed betweenthe hearths, and additional air may be admitted from the Vcentral shaftwhich is hollow. By this means the atmosphere in the furnace may be socontrolled as to be either a reducing or an oxidizing atmosphere. Thebottom hearth of the furnace is air cooled so that the clay ispartiallyl cooled before it leaves the ffurnace. v

From the furnace the clay passes through a "chute 43 to a screw conveyorand cooler 44. This conveyor and cooler is of rthe ordinary screwconveyor type, but is furnished with ajacket through which cold air maybe blown pr through which cooling water may be circulated. At theextreme end of the upperleg of the conveyor there is placed a downwardlyextending chute 45 mmlihi'ajng with tir il; 'wineries 'air c :onveyingthe ground material from the 'ball to a cyclone separator 152! withinwhich; theground'pigment is separatedfromthe a'ir used to convey it. Theseparated"iplgment falls ,from thecyclone separator 52 in to aclassifier Filter clays 'generally contain a certain amount of silicawhich is .non-porous in nature, and

which whenburned becomes hard and abrasive. It practically impossible togrind this material; and it therefore passes sulis'tantially unchangedfrom the ball mill.'j The classifier 53 servesr to separate thisabrasivefmaterial "fromthebalance of the pigment. f The classiiier 5 3may be of the.`centrifugal type in which an airstream floats thellighter material vdepositing it inthe outside ofthe c a'sing,whil e theheavier material drops through to` a second clas'sier. 5 4 of the' sametype. Classier 5 4 serves to lseparate that material vwhich is toocoarse to'be used as `pigment, andl returns it to the'conveyor 4 4through lne55. This material which is too coarse for use as pigment isthen passed through the con@ veyor 44f ,bac k tothe ball mill 41,. Thismaterial isnot'fso abrasive.` as that which wasl removed'inthe,cl'assier l53, butiis merelyinsuclay. 'I'husi-dueto the number ofvariables in' the process itis' impossiblefto' give exactr optimumoperating `conditions;` however, -the opti-v mum conditions can readilybe determined vfor any particular raw materiali andproduct, v

'.Thewater introduced'into the bottom of -pit Ii through perforatedlpipes 1; percolates "up nished pigmenti is withdrawn througfli pipe`56to packing equipment.

If -the furnace is operated with an oxidizing atmosphere rather than areducing atmrosphere, so that substantially all of the carbon is'.burned from the clay, the 'slidefvalve in line 45 is closed and thefullyV burnedvclay is Vpermitted to drop o through line 51 by openingthe slide valve therethrough the 'clay`evenly, and'without channeling,carrying' with it the oii which it removes .amount of clay fines larealso carried upwardwby the water and oil and the mixtureoverflows theweir `II intothe pit I2. Duev tothe practically quiescent state of theoil andwater in'pit I2,the oil 'separates and remains on top and iscarried along by the`belt`l3 to the oil skimmer "I4, Since the oilonjtop is necessarily in a rather-thin layer, some water is removedbythe oil "skimmer I4.' From the skimmer I4 the-oil and water mixture ispassed to a settling tank I6v wherein the oil separates forming a top'layerL'and the`water in, to the second section 58 of the conveyor, e

Aand the fully burned clay is removed through line 59 for storageandre-use in `the filters or for disposal.

Strict conditionsfor the operation of the'presentprocess cannot be setforth, due to the difference's`in filter media and in the oil treated.However, the following will serve as an example: f

The clayis mixed withwater having a temperature of from 120-200 F..inthe eductor 3, and is passed to the"leaching pit 6, which haspeviously"been filled with water atabout -theI same tempera ture. A Theclay settles to the bottom of the pitand when a su'icient charge hasbeen placedtherein, heatedfwater is admitted to the perforated pipes 'I.This water is also from 120-200? F. and has a pH value of about 8, sinceit has been discovered thatif ythe water is neutral 'or en the acid sideit'will not 'properly leach "the clay, as the clay i`s somewhat acid dueto the presence of sulphur compounds in the oil. `'I'he alkalinity visobtained'by theaddition of sodium hydroxide or otherfalkalinematerial tothe water through, valved line 6 0'." By're'gulating the temperature'and pH value of the water the amount4 of oil which will be leached fromthe clay dan be controlled within "desired .limits; an increase ineither or? both the'temfperature or alkalinity ofthe water serving'toincrease the'amount of oil which will be leached vfrom the clay. As fageneral rule the temperature ohosen'for the Waiffel. willbe'that'temperajture at which the oil being filtered is'p'assedthrough vthe 'rilter, thus'when the c layWhiQhf is being v processedinaccordancewith thefpres'entinven- ,.t'ion'is; obtained from a filter'which has been.

handling a light'o'il, which flows'freely'at' a low temperature, the oilwill be at a relatively low settles forming a bottom layer. 'A'floatplaced at the interface of the oil'and water layers operates a valve inthe Water outlet line I'I; From timey to timeoil is drawn ol through theline I 8; Any clay fmeswhich are carried over into the pit I2 settleinto the sump I9 and are removed bythe eductor 20 and returned to' claypit 6 where they are evenly distributed by 'means of a Weir box 22 so asnot to agitate the clay in the pit 6. The pump 24 serves to withdrawsuperfluous water from the pit I2V and to pass a portion of it to theheater 26 and to the lines 8 and -feeding n the perforated pipes ontheoor of -pit`16. AThe pump 30 serves to furnishL water for thetwo ieductors 20 and 3`, as well as to'force water down "which the clay is iatmosphere to revivify it, or toI place it incondil.30% of the containedoil may be, recovered.`:"I`f, "however, the' vclayis to be "burnedin areducing atmosphere and Asubsequently ground to form a tion where it maybev disposed of aswaste,--about black pigment, a lesser percentage ofoil isrecovered sothat when burnedin a reducing atmosphere in thefurnace 42the clay will" contain a considerable amount of 'car-bon.' i

vAfter the clay haslcxeende-watere'd, it is passed to thejfurnace I Hand therein lburned as desired. lf it is to be later ground andutilized:asa pigment; its temperature 4is -controlled'sothatit Adoes not riseabove about 600`F. -Ify-however,

the furnace AIII is operatedwithan oxidizing 'atmosphere therein,I thetemperaturevrnay go to 1000 F. or higher. If the clay is to be revivied,

'the temperature is carefully controlled so as not to harmthe clay, :butif the clay is merely to be 'tive material to remove oil therefromandfto adapt it to further treatment for producing any disposed of aswaste, it may be burned at a higher temperature and thus hasten theburning prcc-v in a reducing atmosphere, considerable carbonfin.

a finely divided state `is adxnixed with lthe clay so that on grindingin the ballmill 41 a finely divided homogeneous iblack pigment' isformed.A

There will be present inthe pigment, however, about 5% of hard abrasivematerial which is of a greaterspecic gravity and of larger particle sizethan vthe pigment.4 It must be removed therefore, in order to form` acommercial pigment. There is also present abo' -t 35% of pigment' whichis not ground to a fine enough degree. The abrasive material istherefore separated in the first classifier 53 and the insumcientlyground pigment is separated in the secf ond separator 54, so that theremaining 60% of the clay passes out through pipe 56 as extremely fineblack pigmentcapable of passing through 4a 325 mesh sieve or :holtenThis pigment may be utilized for any purposes such as paintcompositions, plastic compositions, blacking, etc.

When it is desired-to utilize the clay as a powdered carrier forinsecticides, the clay is re.- moved from the leaching pit and passedbyline l to the rotoscoop 39, wherein it is separated frn the water usedto transmit it through lin 30. It is then passed through the furnace,usually at a higher rate of speed than when it is desired .to burn theclay, and its temperature is controlled to about 300 F. at the outlet43.

vThe outlet temperature, however, will `depend somewhat upon the type ofoil contained in the filter clay. If the oil is extremely light thetemperature may have to be lower than the above stated figure in orderto prevent distillation of the oil during 4the vaporzation of thecontained water, or, on the other hand, if an extremely heavy oil hasbeen filtered by the clay, the temperature may be somewhat higher. Afterthe clay has been dried sufiicientlyit is conveyed tov the ball mill l1wherein it is pulverized so that substantially all of it will passthrough bolting cloth having 200 mesh to the inch. It is usually usableas it passes from the ball mill, but in some cases it may be foundexpedient to use the c'entrifugal classifiers 5I and 54 in order toprovide material of more uniform characteristics.

If it is desired to use the fines which collect in the sump I9 of thesettling pit l2, these nes insteadof being returned to the tray 22 andthence back to the leaching pit i; may be conveyed to a suitablesettling apparatus and the lines then settled, either by gravity or byother means, or, if desired, the mixture of lines pickedup by theeductor 20 may be passed to ltering or centrifugal separating means forseparation.

desired product, .such as revivled clay, black pigment oran inertcarrier for insecticides. It also relates fbroadly to the hereindisclosed method of.4 treating such adsorptive filtering; mate.-l

rial to remove oil therefrom but so as to leavel 'therein a,predetermined proportion of oil and .in

subsequently treating such material to produce the desired product. Italso relates specifically to the productionof an inert carrier forinsecticides. I do not specifically claim herein the herein disclosedmethods of treating the clay to revivify the same orto produce a, |blackpigment. The use of my herein claimed method of leaching Voil from theclay in conjunction with the subsequent burning of the thus treatedclay, from which the oil has been removed, in an oxidizing atmosphere torevivify the clay, forms 'the subject matter of, and is claimed in, mycopending application, Serial No. 217,889, filed July 7, 1938, nowPatent 2,200,145 which is a division of the present application. The useof my herein claimed method of controlling the amount of oil inclay, inconjunction with the subsequent treatment of clay having a regulatedquantity of oil therein, by burning in a reducing atmosphere to producea black pigment, forms the subject -matterof, and is claimed in,.mycopending application Serial No. 217,888 filed July 7, 1938 which is adivision of the present vapplication. A

What I claim and desire to protect by Letters Patent is: -Y

1. The method of treating clay containing adsorbed oil to remove oiltherefrom and adapt the clay for=various uses which comprisesfmixin'gsaid oil bearing clay with water, introducing said mixture of clay andwater into a leaching zone and therein passing additional quantities ofwater through said clay to agitate the same and leach oil therefrom,continuously removing water containing' leached out oil and clay finesfrom said leaching zone and introducing the same into a settling zoneand therein permitting said clay nes to settle out and said oil toseparate out, removing said settled clay fines from said settling zoneand reintroducing them into said leaching zone, skimming oil from saidsettling zone and introducing it into a separating zone and thereinseparating said. oil from any water These fines are then dried,preferably in the furnace Il and `may fbe used as such for carryingagent for insecticides. In some casesit may be advisable to continuouslyfurnish fresh water to the eductor 3 'instead of water which isrecirculated from t e settling pit I2. In this case by settling or othermeans. as disclosed above.

These fines, it will be found, will also serve after drying, and usuallywithout grinding, as carry- Y ins agent for insecticides.

r passing out through line 29. may contain some fines which can berecovered remaining therein, removing said clay from said leaching zone,dewatering the thus removed clay and then drying the same to render saidclay fit for use.

2. The method set forth in claim l in which the water used has a pHvalue greater than '1.

3. The method of treating clay containing adsorbed oil to remove oiltherefrom and adapt theA clay for various uses which comprises mixingsaid oil bearing clay with water; introducing said mixture of clay andwater into a leaching zone and therein! passing additional quantitiesVof water through said clay to agitate the same and leach oil therefromuntil said clay contains a pre-determined quantity of oil, continuouslyremoving water .containing leached out oil and i clay fines from saidleaching zone and introducing the same into a settling zone and thereinpermitting said clay fines to settle outA and said oil to separate out,removing said settled clay fines from said settling zone andreintroducing them into said leaching zone, skimming oil from saidsettling zone and introducing it into a separating zone and thereinseparating. saidoil from any water remaining therein, removing said clayfrom said leaching zone, dewatering the thus removed clay and thendrying the same to render said clay iit for use.

,4. 'I'he method of treating clay containing adsorbed oil to remove oiltherefrom and adapt 'the clay for various uses which comprises mixingsaid oil bearing clay with water; introducing said mixture of clay andwater into a leaching zone and therein. passing additional quantities ofwater through said clay to agitata' the same and leach oil therefrom,continuously removing water containing leached -out oil and clay finesvfrom said leaching zone and introducing the same into a settling zoneand therein permitting said clay fines to settle out and said oil toseparate out, removing said settled clay nes from said settling zone andreintroducing them into said leaching zone, skimming oil from saidsettling zone and introducing it into a separating zone and thereinseparating said oil from any water remaining therein, removing Waterfrom said settling zone and'utilizing the thus removed Water as thewater used for mixing with said clay and that passed through said clayin said leaching zone, removing said clay fromsaid leaching zone,dewatering the thus removed clay and then drying the same to render saidclay fit for use.

5. The method of treating clay containing adsorbed oil to remove oiltherefrom and adapt the clay for various uses whichl comprises mixingsaid oil bearing clay with water, introducing said mixture of! clay andwater into a leaching zone and therein passing additional quantities ofwater through said clay to agitate the same and leach oil therefromuntil said clay contains a predetermined quantity oi oil, continuouslyremoving water containing leached out oil and clay said settling zoneand introducing it into a separating zone and therein separating saidoil from any water remaining therein, removing said clay containing apre-determined percentage of oil from said leaching zone, dewatering thethus removed clay and subjecting said dewatered clay to a dryingoperation at an elevated temperature while controlling the temperatureto prevent distillation and carbonization of the oil during vaporizationof the contained water.

'7. The method of making an `inert carrier for insecticides whichcomprises taking clay which has been used to purify lubricating oils andwhich contains adsorbed oil in excess of the quantity desired in theiinal product which comprises mixing said clay with Water andintroducing the same into a leaching zone, therein passing additionalquantities of water through the clay to thereby leach out excess oilfrom the clay and fines from said leaching zone and introducing the sameinto asettling zone and therein permitting said clay nes to settle outand said oil to separate out, removing said settled clay nesy containinga predetermined quantity of oil from said settling zone, dewatering thethus removed clay nes and drying the same by passing a heated gasthereover at a temperature to dry the same without vaporizing orcarbonizing the oil, skimming oil from said settling zone andintroducing it into a separating zone and therein separating said oilfrom any water remaining therein, removing said clay from said leachingzone, dewaterlng the thus removed clay and then drying the same torender said clay fit for use.

6. A method of making inert carrier for insecticides and the like whichcomprises mixing an amount of oil greater than that desired in the ilnalproduct with a clay-like substance, mixing the thus `formed mixture ofclay and oil-with water and introducing the same into a leaching zonetherein, passing additional quantities ot water through the clay tothereby leach out excess oil from the clay and leave therein apredetermined percentage ot oil, continuously removing water containing'leached out oil and suspended clay Aiilnes :from said leaching zone andleave therein a pre-determined percentage vof oil, continuously removingwater containing leached out oil and suspended clay fines from saidleaching zone and introducing the same into a settling zone, thereinpermitting said clay nes to settle out and permitting oil to separateout, removing said clay nes from said settling zone and reintroducingthem to said leaching zone, skimming oil from said settling zone andintroducing it into a separating zone and therein separating said oilfrom any water remaining therein, removing said clay containing apre-determined percentage of oil from said leaching zone, dewatering thethus removed clay and subjecting said dewatered clay to a dryingoperation at an v elevated temperature while controlling the temperatureto prevent distillation and carbonization of the oil during vaporizationof the contained water.

v8. A method of making inert carrier for insecticides and the like whichcomprises mixing an amount of oil greater than that desired in the nalproduct with a clay-like substance, mixing the thus formed mixture ofclay and oil with water and introducing the same into a leaching zone,therein passing additional quantities of water through the clay tothereby leach out excess oil from the clay and leave therein apredetermined percentage of oil, continuously-` removing watercontaining leached out oil and suspended clay iines from said leachingzone and introducing the same into a settling zone, there' in permittingsaid clay nes to settle out and permitting oil to separate out, removingsaid clay nes from said settling zone and reintroducing them to saidleaching zone, skimming oil from said settling zone and introducing itinto a separating zone and therein separating said oil from any waterremaining therein, continuously removing water from said leaching zoneand utilizing said water as a water used for mixing said 'clay and asthe water passed through said clay in said leaching zone, removing saidclay containing a pre-determined percentage of oil from said leachingzone, dewatering the thus removed clay and subjecting said dewateredclay to a drying operation at an elevated temperature while controllingthe temperature to prevent distillation and carbonization of the oilduring vaporization of the contained water.

' PAUL D. BARTON,`

